Abstract Randomly oriented type I collagen (COL1) fibers in the extracellular matrix (ECM) are reorganized by biophysical forces into aligned domains extending several millimeters and with varying degrees of fiber alignment. These aligned fibers can transmit traction forces, guide tumor cell migration, facilitate angiogenesis, and influence tissue morphogenesis. To create aligned COL1 domains in microfluidic cell culture models, shear flows have been used to align thin COL1 matrices (<50μm in height) in a microchannel. However, there has been limited investigation into the role of shear flows in aligning 3D hydrogels (>130μm). Here, we show that pure shear flows do not induce fiber alignment in 3D atelo COL1 hydrogels, but the simple addition of local extensional flow promotes alignment that is maintained across several millimeters, with a degree of alignment directly related to the extensional strain rate. We further advance experimental capabilities by addressing the practical challenge of accessing a 3D hydrogel formed within a microchannel by introducing a magnetically coupled modular platform that can be released to expose the microengineered hydrogel. We demonstrate the platform’s capability to pattern cells and fabricate multi-layered COL1 matrices using layer-by-layer fabrication and specialized modules. Our approach provides an easy-to-use fabrication method to achieve advanced hydrogel microengineering capabilities that combine fiber alignment with biofabrication capabilities.
Template based chemical vapor deposition (CVD) is a process of effectively fabricating nanostructures such as Carbon nanotube arrays (CNT). During this process, a carbon-carrying precursor gas is used to deposit a layer of solid carbon on the surface of a template within a furnace. Template-based CVD using porous anodized aluminum oxide (AAO) membranes as the template has been applied to efficiently mass-produce CNT arrays which have shown promise for use in gene transfection applications. These AAO membranes are incredibly fragile, making them prone to cracks during handling which can compromise their performance. In order to ease handling of the CNT devices, three-dimensional (3D) printing has been applied to create a support structure for the fragile membranes. The work presented here focuses on the use of 3D printing as a means of integrating CNT arrays into nanofluidic devices, both increasing their useful application and preventing damage to the fragile arrays during handling. 3D printing allows the CNT arrays to be completely encapsulated within the fluidic device by printing a base of material before inserting the arrays. Additionally, 3D printing has been shown to create an adequate seal between the CNT arrays and the printed device without the need for additional adhesives or sealing processes. For this work, a commercially available, fused deposition modeling (FDM) 3D printer was used to print the devices out of polylactic acid (PLA) plastic. This approach has been shown to be effective and repeatable for nanofluidic device construction, while also being cost effective and less time consuming than other methods such as photolithography. Cell culture and has been demonstrated using HEK293 cells on the devices and was found to be comparable to tissue culture polystyrene.
Microfluidic tissue barrier models have emerged to address the lack of physiological fluid flow in conventional "open-well" Transwell-like devices. However, microfluidic techniques have not achieved widespread usage in bioscience laboratories because they are not fully compatible with traditional experimental protocols. To advance barrier tissue research, there is a need for a platform that combines the key advantages of both conventional open-well and microfluidic systems. Here, a plug-and-play flow module is developed to introduce on-demand microfluidic flow capabilities to an open-well device that features a nanoporous membrane and live-cell imaging capabilities. The magnetic latching assembly of this design enables bi-directional reconfiguration and allows users to conduct an experiment in an open-well format with established protocols and then add or remove microfluidic capabilities as desired. This work also provides an experimentally-validated flow model to select flow conditions based on the experimental needs. As a proof-of-concept, flow-induced alignment of endothelial cells and the expression of shear-sensitive gene targets are demonstrated, and the different phases of neutrophil transmigration across a chemically stimulated endothelial monolayer under flow conditions are visualized. With these experimental capabilities, it is anticipated that both engineering and bioscience laboratories will adopt this reconfigurable design due to the compatibility with standard open-well protocols.
Increase in demand of Green energy and environmental issues of carbon emission Renewable energy sources are getting more attraction and development day by day. Among different renewable energy resources wind energy is assumed to be more friendly towards the green environment. In order to capture the maximum benefit large wind forms are deployed in many countries which are connected to different power grid in order to fulfill the energy requirement of the country. This increased penetration of wind farms raised many challenges like the dynamics and quality of power system. It is evident from the previous work on wind turbines, which have pad mount transformers take more time for calculation and hence are not suitable for research. There is a need to have an alternate technology that is more efficient. This paper uses a systematic approach to propose an alternative model. We verified proposed alternative model by matching the results of both equivalent and large wind farm uniform models for power flow and transient stability analysis in power world simulator and obtained same results for both models.
Leukocytes navigate through interstitial spaces resulting in deformation of both the motile leukocytes and surrounding cells. Creating an in vitro system that models the deformable cellular environment encountered in vivo has been challenging. Here, we engineer microchannels with a liquid-liquid interface that exerts confining pressures (200-3000 Pa) similar to cells in tissues, and, thus, is deformable by cell generated forces. Consequently, the balance between migratory cell-generated and interfacial pressures determines the degree of confinement. Pioneer cells that first contact the interfacial barrier require greater deformation forces to forge a path for migration, and as a result migrate slower than trailing cells. Critically, resistive pressures are tunable by controlling the curvature of the liquid interface, which regulates motility. By granting cells autonomy in determining their confinement, and tuning environmental resistance, interfacial deformations are made to match those of surrounding cells in vivo during interstitial neutrophil migration in a larval zebrafish model. We discover that, in this context, neutrophils employ a bleb-based mechanism of force generation to deform a barrier exerting cell-scale confining pressures.
Introduction Primary percutaneous coronary intervention (PPCI) in ST-elevation myocardial infarction (STEMI) patients can lead to poor outcomes. Intra-coronary thrombus development due to atherosclerotic plaque rupture and coronary blood flow blockage causes STEMI. Intracranial thrombosis in STEMI patients is fatal. It was our goal to establish how often patients with STEMI underwent PPCI with a high thrombus burden versus a low thrombus burden and to compare the mean monocyte count between the two groups. Material and methods This cross-sectional study was conducted at KRL Hospital Islamabad from October 2021 to March 2022. At a 95% level of confidence, a 5% margin of error, and keeping a population size of 330, a sample size of 178 was obtained using the Raosoft sample size calculator (Raosoft, Inc., Seattle, WA). The non-probability consecutive sampling method was used. All patients with STEMI undergoing PPCI, aged between 18 and 80 years, and presenting within 24 hours of symptoms were included in our study. Pre-PPCI pharmacological treatment given within three hours of the onset of a heart attack to stabilize patients with myocardial infarction included aspirin, clopidogrel, and an intravenous bolus of 70 U/kg of body weight of un-fractionated heparin. The collected data were analyzed using SPSS version 26.0 (IBM Corp., Armonk, NY). Fisher's exact test was employed, and a p-value of less than 0.05 was deemed statistically significant. The odds ratio and confidence interval were also calculated. Results A total of 178 participants were included in the research, out of which males were predominant with more than half of the study population. The mean age in patients having a low thrombus burden was 37.75 ± 6.39 years and that of patients with a high thrombus burden was mean 56.04 ± 7.98 years. In high thrombus burden patients, diabetes mellitus was found in 98.3%, hypertension in 120 patients (100%), obesity in (60%), and tobacco consumption in 120 patients (100%). The mean monocyte count in high burden patients was 70.27 ± 3.24, whereas it was 61.89 ± 5.71 in low burden patients. Only five patients had a Thrombolysis In Myocardial Infarction (TIMI) score of 5 while 34.8% of patients arrived in three to six hours and 12.9% arrived in less than three hours. Patients with a high monocyte count have 1.3 times more chances of developing the disease when the monocyte count was high (OR = 1.318, 95% CI = 1.140-1.524). Conclusion Patients with STEMI undergoing PPCI had a higher monocyte count upon admission, which was an independent clinical predictor of a high thrombus burden. Our findings suggest that admission monocyte count may be available for early risk stratification of high-thrombus burden in acute STEMI patients and might allow the optimization of anti-thrombotic therapy to improve the outcomes of PPCI.
Abstract Microfluidic platforms use controlled fluid flow to provide physiologically relevant biochemical and biophysical cues to cultured cells in a well-defined and reproducible manner. In these systems, undisturbed flows are critical and air bubbles entering microfluidic channels can result in device delamination or cell damage. To prevent bubble entry, we report a low-cost, R apidly I ntegrated D ebubbler (RID) module that is simple to fabricate, inexpensive, and easily combined with existing experimental systems. We demonstrate successful removal of air bubbles spanning three orders of magnitude with a maximum removal rate (dV/dt) max = 1.5 mL min −1 , at flow rates corresponding to physiological fluid-induced wall shear stresses (WSS) needed for biophysical stimulation studies on cultured mammalian cell populations.
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